The Changing Population Structure of Gulf of Maine Haddock: Insights from the 1920s

Haddock (Melanogrammus aeglefinus) has been a mainstay of New England’s commercial fishing fleet for more than a century. Historically, these stocks are characterized by dramatic, cyclic variations in landings, though it remains unclear why this occurs.  Haddock stocks in 2010 are reported to be fully recovered; yet, stocks along the northern 1/3 of New England’s coastal shelf collapsed more than three decades ago and in the absence of significant fishing activity, still show few signs of recovery.  Little is known about why haddock stocks along this 200 km coastline and its bordering 9,000 km² of historically productive fishing grounds has failed to recover or what factors may be inhibiting recovery. To better understand what changes may have occurred there, possible causes of the collapse are examined by analyzing haddock distribution and behavior from the 1920s, a period when haddock and related groundfish stocks were more robust.  Fishermen’s ecological knowledge (FEK) gathered during the 1920s and applicable scientific literature was used to establish a baseline of seasonal haddock distribution patterns. The resulting data was displayed on a geographical information system (GIS) and their movements among 1920s fishing grounds were tracked, based on seasonal changes in the relative abundance value on each ground.  This allowed fine-scale spatial and temporal variations in distribution to be used to evaluate population structure and site fidelity. Several localized spawning components in the study area were identified that appeared to be associated with nearby coastal spawning areas and moved in concert with juvenile alewives. The discussion addresses variations in recent haddock behavior from 1920s studies and their possible causes. The study area includes northern Gulf of Maine (GOM) from Cape Cod Bay to Bay of Fundy, with particular emphasis on the northeastern-most U. S. waters. Haddock are the third in a series of 1920s gadids to be studied.